Semiconductive polymeric coatings for outdoor polymeric insulation

In the following paper the development of a semiconductive coating for medium voltage outdoor insulator is presented. The coating based on silicon rubber and semiconductive fibers shows resistivity in range of 10 MΩ/□ which allowed for increasing of the insulator temperature 8 °C above the ambient after energizing with 12 kV. Outdoor testing was performed at Koeberg Insulation Pollution Test Station. The developed coating presented superior performance compared to a standard outdoor epoxy insulator. Moreover in contrary to traditionally made ceramic glazes the semiconductive coating shows positive thermal coefficient of resistance (PTCR) eliminating the risk of thermal runway.